It is well known to produce a modified thermoplastic resin by subjecting a thermoplastic resin to a modifying reaction in molten state in extruding machine. Hitherto, modifying reactions, such as grafting, cross-linking and so on, have been realized in industrial scale using such a technique as above. For instance, graft-modified polyolefin resins have found wide applications for those including modification of paints, adhesion onto polar substances and so on. In particular, modified polyolefin resins obtained by grafting an ethylenically unsaturated carboxylic acid or a derivative thereof onto polyolefin resins reveal superior modifying performance and, above all, modified polyolefin resins obtained by grafting maleic anhydride onto polyolefin resins have found wide applications for adhesive resins exhibiting favorable properties for, for example, packaging of foods etc.
However, conventional processes for producing modified thermoplastic resins by effecting the reaction for modifying thermoplastic resins in molten state result in lower efficiency and insufficient uniformity of the reaction, in addition to a problem of greater trend of the unreacted components to remain in the resulting modified thermoplastic resin.
On the other hand, so-called solution process has also been practically used as a technique better in the efficiency and uniformity of the reaction, in which an organic solvent is used as the reaction medium. However, this technique is difficult to apply for a continuous production on an extruding machine and has lower productivity due to inevitable use of batchwise production process, in addition to the problem of higher production costs due to the employment of expensive organic solvent which require bothersome handling measures.
An object of the present invention is to provide a process for producing modified thermoplastic resin, in which the efficiency and the uniformity of the modifying reaction can considerably be increased without having recourse to the use of organic solvent as the reaction medium and, in addition, the remainder of the unreacted components remaining in the resulting modified thermoplastic resin can be decreased to a marked extent and the modified thermoplastic resin can be produced easily at a lower cost in an efficient manner.
Another object of the present invention is to provide a modified thermoplastic resin obtained by such process.